Coconut hard shell granular infill for synthetic sport fields

ABSTRACT

A coconut material comprising short fibers having a length in a range of 0.5 to 25 millimeters. A method to produce short fibers includes processing coconut husks to separate coir material comprised of pith and fiber from the husks, separating short coconut fibers having a length in the rage of 0.5 to 25 millimeters from the coir material, and packaging the short coconut fibers. The method may include softening the short fibers.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-in-Part U.S. patent application Ser. No. 17/287,075, filed Apr. 20, 2021, which is a § 371 of PCT/US2019/060760, filed Nov. 11, 2019, which claims priority to, and the benefit of U.S. Provisional No. 62/767,567 filed Nov. 15, 2018, both of which are incorporated herein by reference in their entirety.

BACKGROUND

Synthetic sports fields typically have synthetic turf fibers on top of an infill material. The infill material allows the field to have a slight grade to it from the center of the field to the sides to allow for better drainage, and helps protect the players by providing shock absorption, traction, and foot stability. Currently, most infill material consists of rubber crumbs, which mostly come from recycled tires.

There are several disadvantages to rubber crumbs. It is not very environmentally friendly, being made from recycled tires. While being able to use the tires for the crumb is better than the tires filling up landfills, the crumbs themselves are not biodegradable either. In addition, there has been some data indicating that they are carcinogenic.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the parts of a coconut and the hard shell used for crumb infill.

FIG. 2 shows a diagram of an embodiment of synthetic turf with coconut crumb infill material.

FIG. 3 shows an embodiment of a method of producing coconut crumb infill.

FIGS. 4-6 show examples of a hammer mill.

FIG. 7-8 show examples of a shredding machine.

FIG. 9 shows a view of the coconut crumb infill.

FIG. 10 shows a flowchart of embodiments of a process to produce short coconut fiber material.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The use of infill in synthetic turf fields is governed by the Synthetic Turf Council (www.SyntheticTurfCouncil.org), which has produced several documents including “Guidelines for Synthetic Turf Performance,” published in December, 2011, and “Guidelines for Crumb Rubber Infill Used in Synthetic Turf Fields,” which were approved in October of 2010. Any material replacing the crumb rubber infill will need to meet the same or similar requirements. One issue that arises is that even if the material is intended as infill, it ends up on top of the turf and will come into contact with the people on the field. It is also somewhat intrusive ending up in shoes, equipment bags, inside players' clothes, etc. High levels of contact between the crumb and the users will occur.

While the use of recycled tires as an infill material has some advantages, concerns have been raised about the health effects of tire crumb. Tire crumb is not just used as infill for sporting fields but is also used as cushioning material in playgrounds. The EPA began a study in 2016 about the health concerns of tire crumbs (www.epa.gov/tirecrumb).

Coconut hard shell material can meet the above standards without health concerns, being an all-natural substance. Coconut shell has high lignin and cellulose content, and the casing contains materials that are resistant to bacteria and fungi. Other uses of coconut shell exist, including in the manufacture of mosquito coils, incense sticks, in plywood manufacturing as a phenolic extruder, and as filler in the manufacture of resin glue.

As used here the term “coconut crumb’ means one or more particles of the hard inner shell of a coconut cut down to particles typically having a size in the range from 4-7 millimeters, inclusive, but may include any crumbs of smaller than 10 mm. The term “coconut chips” means one or more particles of the hard outer shell of a coconut cut down to particles having a size in the range from 20 to 40 mm, inclusive, by may include any crumbs larger than 20 mm. These ranges are estimates but are intended to differentiate between particles that are 20 mm or larger, which are called chips, and particles that are 7 mm or smaller, called crumb. The term “coconut crumb infill” and “coconut crumb” are intended to be interchangeable.

FIG. 1 shows a coconut 10 split open, with its husk 12 next to it. The hard inner shell is what is of interest here, but it helps to clarify by looking at the other portions of the coconut. The white innermost material 14 is typically referred to as its ‘meat’ ‘copra’ and contains coconut water. The layer of spongy material 16 between the meat and the outer shell is referred to as ‘pith’ with ‘coir’ and ‘fiber’ Pith is highly absorbent and has uses with shell infill materials that may be appropriate here, as an infill amendment to the coconut shell infill. The hard outer shell 18 is what is also of interest here.

FIG. 2 shows a view of a synthetic turf field using coconut crumb infill instead of tire crumb infill. As can be seen in the diagram, infill 20 is the second layer from the top and has a grade such that the finished field has a slope from the center of the field to the sidelines to allow for drainage. The synthetic turf lies 22 on top of the coconut crumb infill. Underneath the coconut infill, there may be many layers. In this example, there are layers of a thick, resilient shock and drainage pan 24, a geotextile fabric 26, a compacted aggregate leveling course 28, a compacted aggregate base course 30, a layer of subbase material 32, and the compacted subgrade material 34. The selection and configuration of these materials is left up to the system designer, but in general the coconut crumb and replace the tire crumb as infill with no modifications of the underlying layers of the field.

FIG. 3 shows an embodiment of a process for converting the hard inner shell of coconuts to coconut crumb. This process begins with the outer shell “skin” of the coconut 40. Typically, a coconut shell crusher opens the shells. The process then removes and discards the meat and the water. The shells then typically undergo cleaning and sanitization and dried to under 10% water content, not shown here.

The process starts with the coconut shells being run through some sort of shredding or breakdown machine at 42, such as a hammer mill and/or a shredder to produce coconut chips and waste material, referred to as ‘fines’ 44. This process typically reduces the coconut shells to chip sizes in the 20-40 millimeter range. The resulting material is then screened at 46 in which the material that is not of the right size, fines, 48, is either designated as waste material, but may be used in other processes. Some of it may be returned to the beginning of the process at 40 for reprocessing.

A conveyor 50 then moves the coconut chips 52 to a second breakdown process at 54. One should note that the embodiment shown in FIG. 3 shows a hammer mill, but any machine that can break down the hard coconut shell into the desired sizes, referred to here as a ‘breakdown’ machine, would work in this process. The resulting material 56 from the second breakdown process will typically comprise a mix of coconut crumb and fines. This material then undergoes screening at 58, with the waste materials or fines being recycled or used for other processes. The resulting coconut crumb can then become turf field infill.

FIG. 4 shows a diagram of a hammer mill 70. The mill typically has a chute or other opening 72 to allow delivery of the coconut shells to the inner workings of the mill. The hammers 78 rotate around a rotor with hanging metal knife blades that drives them to break up the coconut shells into the chips and round off the jagged edges. A screen such as 78 traps the chips to undergo further processing and the waste material, also referred to as ‘fines’ are taken away. Note that this screening may comprise the screening process mentioned above or may be prior to the screening. FIG. 5 shows a hammer mill 70, and FIG. 6 shows embodiments of the different screens 78.

Some embodiments of the process may rely only upon a single hammer mill as the breakdown machine, with the hammers changed between the breaking down of the shells into coconut chips and coconut crumb. The user can also adjust the rotor speed to be coordinated with the screen type to ensure the output meets a size specification. For shredders, it may involve changing the size of the blades. Some embodiments may use two of one type of breakdown machines such as two hammer mills or two shredders. Some of the embodiments may rely upon a combination of different types of breakdown machines, using one type to produce coconut chips and another type to turn the chips into crumb.

Returning to FIG. 3 , the material trapped by the screen is then removed from the hammer mill and conveyed to another hammer mill. As mentioned above, one should note that the second breakdown machine may comprise the same breakdown machine after the machine is recalibrated. In this embodiment, using blunt hammers within a hammer mill, the screens and/or the hammers are changed to reduce the chips to a smaller size, plus round or blunt the sharp edges of the crumbs. The chips, meaning portions of the outer shell having sizes in the range of 20-40 millimeters, undergo further processing to reduce their sizes to ‘crumbs,’ meaning that they have a size in the range of 4-7 mm. The further processing also serves to smooth out the edges and remove sharp corners from the crumbs.

Other methods of reducing or breaking down the coconut outer shells to the hard granular crumbs are of course possible. For example, instead of using a hammer mill, one could employ a shredder as shown in FIGS. 7 and 8 .

FIG. 7 shows an example of a shredder machine 80 with its outer layer of blades or teeth such as 82. These can grind up the coconut husks to a first chip size. The user selects the blade size to achieve the desired chip size. Inner teeth or blades such as 84 shown in FIG. 8 can then grind the chips into the crumb size. The shredder 80 may incorporate a screen located at the bottom to perform the screening or may just have an outlet that produces the coconut crumb to undergo a separate screening process.

Any method that reduces the size of the coconut husks to the crumb size without leaving any sharp corners or loose material behind will suffice to convert the coconut husks into coconut crumbs. These are then useful as infill in the synthetic turf as shown in FIG. 2 .

FIG. 9 shows an embodiment of the resulting crumbs. FIG. 9 shows a hand to provide a sense of scale of the resulting crumbs. As mentioned above, the crumbs typically have a size in the 4-7 mm range, but any particle at 10 mm or below falls under the label of ‘crumb.’

In another embodiment, the hard shell granulars, or crumb, can include coconut fibers. As discussed above, the material in between the hard outer shell or husk and the hard inner shell comprises coir, usually a combination of the spongy pith material and fibers. In most coir processing, the fibers are disfavored, as they alter the overall properties and texture of the material.

Typically, the short fibers are discarded. The long fibers may be used in yarns and ropes, floor coverings and mats, brush, and broom bristles, and as mattress fill material. Traditionally, hand processing of the husks and fibers can pollute water, as the husks are soaked in brackish water for months that can lead to runoff and pollution. After soaking to loosen the fibers, laborers loosen the fibers by hand and clean them. The residual pith has found uses in horticultural products, as discussed above. Mechanical processes, such as a defibering machine, separate the long fibers from the short fibers. The short fibers are typically discarded.

Currently, some machines shred the “waste” material to allow easier disposal of it. Shredding machines generally reduce the coir material of fiber and pith into smaller pieces so they can be recycled or disposed of. A newer body of machines have become available that cut the longer fibers to shorter fiber lengths.

However, the inventor has discovered that “short” fibers can increase the efficacy of the material used as an infill, in combination with the hard shell granulars and one its own. As used here, a “short” fiber has a length of between 5-20 mm, a length of between 5-25 mm, or a length of 5-30 mm. In some instances, the short fibers may be as short as 0.5 mm at the low end, with the upper end of the range being as above. The short fibers stabilize the loose pith material and helps it to lock the pith material to the artificial turf fibers.

In one embodiment, where the short fibers and the pith are used together, the material has a mix of 40 percent pith and 60 percent short fibers with no hard shell granulars. In other embodiments, the material may comprise the hard shell granular, the pith and the short fiber, other embodiments may comprise the hard shell granulars with just the short fibers.

Generally, processing of coir material involves removing the outer husks and discarding them, and then shredding, grinding, and/or hammering the coir material in a series of machines at a first size, screening the material to remove portions that are too large, then repeating the process, following by another screening. Depending upon the machinery used, the machines may include large spinning drums with screens similar to those shown in FIG. 7 that allow the pith to exit the drum while the fibers are retained. This process separates the fibers from the pith, as discussed above. However, one can alter the process to ensure that the short fibers pass through the screens while the longer fibers remain. Alternatively, the long fibers could be cut to produce short fibers.

As mentioned above, many processes discard the short fibers and the pith, also referred to a cocopeat or coconut peat. Recently, pith has gained favor as a horticultural material, and the long fibers have been used as mattress fillers, rope, yarns, and mats. One can adapt the processes used to process the coconut material to produce different mixes of material that include the short fibers. FIG. 10 shows a flowchart of the production of the various mixes.

In FIG. 10 , the particular “mix” produced identifies the path of the different subprocesses. Initially, the husks are processed. Most coconut processes want the inner brown shell and meat, sometimes call the “seed,” and treat the husk and coir as waste. Depending upon the machinery used, the husk may undergo grinding, or processing by a defibering machine. Whatever machinery used by the process, it begins with obtaining the coir material at 90.

In one embodiment, the husk may be cut or diced into cubes and then ground or shredded to separate the husk from the fibers. The cutting may be accomplished by one machine, with the grinding or shredding accomplished by another.

The first mix in the process comprises just the short fibers. Again, depending upon the machinery and process used, path “1” may separate the long fibers from the short fibers at 94 first, then separate the pith from the fibers at 92. Alternatively, it may separate the pith from the fibers first at 92, and then the long fibers from the short fibers at 94, or it may do both at once. One should note that the term “separating” long fibers from short fibers may involve cutting long fibers to make short fibers. The cutting process may also involve twisting the long fiber into ropes, similar to making rope but not necessarily weaving the fibers, and then cutting them to make short fibers. The short fibers alone are then packaged at 96.

The second mix comprises the short fibers and the hard shell granulars. Once the process has separated the coir from the shell, the shell material may be discarded or undergo processing as discussed above to produce the hard shell granulars, used for mixes “2” and “4.” The process for the “2” mix at the beginning is the same as for “1,” in that only the short fibers are desired, with no pith or long fibers. At 100, the hard shell granulars are added to the short fibers and then the mix undergoes packaging at 96.

The third mix comprises the short fibers and pith. For the “3” mix, the process moves from 90 to 94, and may not include 92. If the machinery used combines the separation of the fibers and the pith in one step, an additional step, not shown, may add the pith back into the mix. This will also be true for mix “4.” Mix “3” comprising only the short fibers and pith would then undergo packaging.

Some sports field applications would prefer not to include fiber, some infill mixes comprise a very high percentage of pith with very low fiber content. However, low fiber content may result in the pith blowing in the wind, or being somewhat loose and unstable that causes it to not stay in place. Adding in small fiber to the high pith mix makes a more uniform texture. The short fiber interlocks with the pith, making it more stable and less likely to blow away or move.

The fourth mix comprises the short fibers, the pith and the granulars. As mentioned above, if the fiber separation and pith separating happen at the same time, the process may need to add the pith back into the mix, similar to when the hard shell granulars are added at 102.

The process flow used depends upon the machinery, and the process flow can adapt and add to the machinery processing as needed to retain the short fibers, and then to mix them with the other components, as well as many others, as needed.

In this manner, one can use an environmentally friendly, where otherwise waste product of coconut shells replaces the non-biodegradable tire crumbs currently in use on synthetic turf fields. The hard shells of the coconuts do not absorb water in a significant amount when wet, have antifungal characteristics, and while they will over time degrade, it is much less expensive and cost effective to replace them. The material is organic, sustainable, renewable, and safe for people and pets.

In addition to the sports field applications, the short fibers may have uses in agriculture, from home gardens to industrial-scale farms. U.S. Pat. No. 11,758,855, issued Sep. 19, 2023, “TURF AND LAWN COIR,” discusses this type of use and is incorporated by reference herein in its entirety. Using short fibers in any of the above mixes for garden applications is fully within the scope of the claims.

Further, the short fibers in any of the mixes above, or by itself, may undergo buffering. In the process of buffering, the fibers in any mix would be treated to alter the cation exchange capacity (CEC) of the material. Buffering increases the amount of magnesium and calcium, while reducing the sodium and potassium, of which coir naturally has higher amounts. The buffering process exposes the coir material with a solution of low EC (electrical conductivity) water. The buffered water may include calcium nitrate, magnesium, or both, as well as other materials that lower the EC of the water, while having the desired effect on the sodium and potassium in the material. U.S. patent application Ser. No. 17/153,614, filed Jan. 20, 2021, “BUFFERED COCO MATERIAL,” describes this process, and is incorporated by reference in its entirety herein.

The short fibers may take on a consistency similar to cotton or wool, short, curled fibers in a group that have a texture similar to cotton or wool. This discussion may refer to this a “cocowool.” The fibers in this form may be rough and somewhat hard and brittle, so may benefit from a softening process. The softening process may occur before or after production of any of the mixes above, such as after step 90 in FIG. 10 , or before packaging at 96.

In one embodiment, the softening process may involve water/steam alone, or may include a softening agent. One embodiment involves spraying the cocowool with a 50%-50% mixture of water and alcohol, such as rubbing alcohol, onto the fiber. The process allows the mixture to penetrate the cocowool over time, such as up to 24 hours. Other softening agents in addition to alcohol include ammonia and mineral oils, as examples. The process may use the softening agent alone or may use it mixed with water and/or any other softening agent(s).

Alternative embodiments only use water. In one embodiment, the cocowool is soaked in water and then aged in a humid environment. Another embodiment applies high pressure/high temperature steam over 24 hours. One embodiment of steaming the fiber comprises placing all the fibers in a chamber, and then heating the chamber with steam above the boiling point of water (212 F, 100 C). Steaming loosens up the bonds between the fiber and water will penetrate through the upper layer of the fiber to saturate the fiber cells with water. Softening by steam does not harm the exterior or interior structure of the fibers. If, after undergoing steaming for 24 hours, the fibers are still hard, they can be returned to the chamber for more softening. After steaming to soften the fibers, they are then dried.

It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the below claims. 

What is claimed is:
 1. A coconut material comprising short fibers having a length in a range of 0.5 to 25 millimeters.
 2. The coconut material as claimed in claim 1, further comprising coconut pith mixed with the short fibers.
 3. The coconut material as claimed in claim 2, wherein the coconut material comprises pith in a percentage in the range of 30 to 50 percent and the short fibers in a range of 50 to 70 percent.
 4. The coconut material as claimed in claim 1, further comprising hard shell granulars mixed with the short fibers.
 5. The coconut material as claimed in claim 4, further comprising coconut pith mixed with the short fibers and the hard shell granulars.
 6. The coconut material as claimed in claim 1, wherein the fibers have a consistency similar to wool.
 7. The coconut material as claimed in claim 1, wherein the coco material is buffered.
 8. A method, comprising: processing coconut husks to separate coir material comprised of pith and fiber from the husks; separating short coconut fibers having a length in the rage of 5 to 25 millimeters from the coir material; and packaging the short coconut fibers.
 9. The method as claimed in claim 6, wherein processing the coconut husks comprises removing pith material from the fibers.
 10. The method as claimed in claim 8, wherein separating the short coconut fibers from the coconut fibers comprises sorting the short fibers from the coconut fibers.
 11. The method as claimed in claim 8, wherein separating the short coconut fibers from the coconut fibers comprises cutting the coconut fibers to produce short coconut fibers.
 12. The method as claimed in claim 11, wherein cutting the coconut fibers comprises twisting the long fibers into long ropes and then cutting the ropes into short fibers.
 13. The method as claimed in claim 8, wherein packaging the short coconut fibers comprises packaging the short coconut fibers alone.
 14. The method as claimed in claim 8, wherein packaging the short coconut fibers comprises packaging the short coconut fibers with pith material.
 15. The method as in claim 13, further comprising adding pith to the short coconut fibers.
 16. The method as claimed in claim 15, further comprising mixing the short coconut fibers with the pith material to produce a mixture in which pith material comprises a percentage in a range of 30 to 50 percent of the mixture.
 17. The method as claimed in claim 8, wherein packaging the short coconut fibers comprises packaging the short coconut fibers with hard shell granulars.
 18. The method as claimed in claim 17, wherein packaging the short coconut fibers comprises adding coconut pith material.
 19. The method as claimed in claim 8, further comprising buffering the short fibers with a solution of calcium nitrate.
 20. The method as claimed in claim 8, further comprising softening the short fibers. 